Trying to get 4.4.2 with root - Starting from unrooted device - Stuck on Sony logo

I have a C6903 and I decided it about time to get root permission (I prefer without unlocking the boot-loader even though I have already backedup TA )
My ultimate goal is 4.4.2 rom with root .

After searching on xda I have found rom that I want :
RomAur v6.2
But it requires :
And therefore I understood that I have to go through another version of 4.4 , so I need to flush:
[STOCK] [C69XX] [4.4] Update to 14.3.A.0.681 [Root & XZDR] [UPDATED]
This rom both for locked and unlocked bootloaders.

I realized that in order to install the this rom I have to go through several steps:1 . flushing C6903_14.1.G.1.534_ [ NUT ] . ftf with flashtool ( so I could perform root)2 . getting root and flushing recovery with a Z1 - lockeddualrecovery2.7.100 - BETA.installer.zip ( this is the latest version and it has install.bat file, selecting 3 in the dos menu performs root, after restarting the device I update the SuperSU via googleplay and then I got root).

The goal is to reach 4.4, I understood that I must pass through another version :

At the moment I'm on C6903_14.1.G.1.534 (after I got the device rooted and installed recovery mode) , so I need to flush :

I did everything exactly according the instructions :
All the steps until 10 includes step 10.

And no matter what I tried , the device stuck in boot screen ( I gave it 15 minutes to be stuck on this screen ) :

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